<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.10/vue.js"></script>
    <style>
        .one{
            width: 100px;
            height: 100px;
            background-color: yellowgreen;
        }
        .two{
            width: 200px;
            height: 200px;
            background-color: skyblue;
        }
        .three{
            width: 250px;
            height: 250px;
            background-color: pink;
        }
        .active{
            color: royalblue;
        }
    </style>
</head>
<body>
<div id="app">
    <div :class="['one','two','three']"></div>

    <div class="public" :class="boxClass"></div>
</div>
<script>
    const vm = new Vue({
        el:"#app",
        data(){
            return{
                boxClass:["one","two","three"]
            }
        }
    })
</script>
</body>
</html>